Automatic telephone system



Sept. 3, 1929. H. M. FRIENDLY 1,726,933

AUTOMATIC TELEPHONE SYSTEM Filed July 14, 1927 5 Sheets-Sheet 1 illSept. 3, 1929. H. M. FRIENDLY 1,726,983

AUTOMATIC TELEPHONE SYSTEM Filed July 14, 1927 5 Sheets-Sheet 2 Elseirk-FIE]- E- I I Ii: 1. 'I. I I

Inventor- RE I A11 Sept. 3, 1929. H. M. FRIENDLY AUTOMATIC TELEPHONESYSTEM Filed July 14, 1927 5 Sheets-Sheet 5 Sept. 3, 1929. H. M.FRIENDLY 1,726,933

AUTOMATIC TELEPHONE SYSTEM v Fil uly 14. 1927 5 Sheets-Sheet 4'=======acn==u===a=n==n Inveniur Herb efi-Pl-Frien dg Ali sept- 3, 1929-H.'M. FRIENDLY 1,726,983

AUTOMATIC TELEPHON SYSTEM Filed'J'u'ly 14, 1927' 5 Sheets-Sheet 5Tuwdrds 152-552- 6;, Marg- Herherz-PfFriandlQ UNITED STATES PATENTOFFICE.

nnmsnn'r M. FRIENDLY, or CHICAGO, ILLINOIS.

AUTOMATIG TELEPHONE SYSTEM.

Application filed July 14,

The present invention relates to telephone systems; more particularlyso-called automatic or machine switching telephone systems Generalobjects.

The general object of the present inventionis to enable the operatingconcern to establish rates'for telephone service for automatic ormachine switching telephone systems which will operate to discouragetraflic at logical periods of densest trailic and to encourage traflicat logicalqperiods of lightest trafiic. Reference is made to myco-pending-application for U. S. Letters Patent, Serial No. 191,578,filed May 16th, 1927, with particular reference to the preamblethereofswherein the eco-' nomic phases of applying service charges inthe general manner contem plated by the present invention is discussed,but with particular reference to manual telephone systems. The generaladvantages accruing to the invention involved in the saidco'-pending-application hold for the'present invention.

.Reierence is also made to my patents 1,694,169 granted Dec. 4, 1928,and 1,694,170, granted Dec. 4, 1928. Reference is further made to mycopendingapplication Ser. No..

481,259, filed J une 29, 1921, with particular reference to switches Band C therein.

However, the present invention has specific objects and structure. Amongthe features of the present invention are a. Means requiring the placingof a coin.

(or token) in a pre-payment collector forming a part of thecallingsubscribers station so that unless the coin is first placed inprepayment device (P) the means forautomatically directing the centralofice automatic switching equipment will continue disabled. Broadly,this feature is not new in the art.

1). Means whereby the timing of the connection will start responsive tothe called subscriber responding, and wherein through the agency of atiming switch auxiliary to the first numerical selector of the switchtrain, the

period the connectionmay be held for a specific toll charge will vary inaccordance with the time of day through which the connection endures.

a. Means whereby a specific tone will be applied audible to the partiesof the connection to apprise them that a'substantially definite timeremains before the termination of the period allowed for thepredetermined toll charge.

1927. Serial No. 205,650.

d. Means whereby a final tone will be applied audible to the parties ofthe connection to apprise them that the coin has been de posited in thecompany till and that the period.

coin is not inserted as pre-payment for the next succeeding period.

6. Means whereby the predetermined time a connection may endure for thefixed predetermmed cost will be lengthened for succeedmg periods afterthe first period of a maintained connection while the rate for initialpenods remains the same. That is, the second and succeeding periodswill'be longer for the same time of day for connections which aredurating.

7. Means whereby the coin will be refunded upon the calling subscriberhanging up his telephone receiver if the party called does not respondor if the line called is that of a free subscriber so far as incomingcalls are concerned. The lines extending to the information, complaintand other departments of the operating concern would come under thelatter class of lines. I

g. Means whereby the coin will be refund ed upon the calling subscriberabandoning of the day, though it will be optional with himby depressinga button at his telephone to transfer the charge to the callingsubscriber for any of these calls. The latter calls may be callsappertaining to, matters other than orders for his wares. The hoursduring which the grocer may assume charges for calls may be logicaloff-peak times and wherein the operating concern may make a special ratefor calls of predetermined duration; perhaps of shorter duration thanallowed to subscribers generally for the fixed predetermined prepaymentcharge in force at that time of day. The latter takes into considerationthat in automatic systems the time of holding a connection is thedetermining factor of cost to the operating concern, almost wholly,since no manual efi'ort is applied by it in efiecting to avoid futilecalls for which no revenue is derived from the calling subscriber by theoperating concern. It is desired that the called subscriber desist fromusing the called line or provide a group of sufiicient number of linesto carry all trafiic offered during said certain hours.

j. A salient feature of the present invention is the feature forrefunding the coin to the calling subscriber in the event the primaryline switch or the concerned secondary line switch is not able to extendthe connection due to all available outgoing trunks therefrom beingbusy; this responsive to the calling upon caring the specific tonedenoting that the call is futile.

70. Another feature of the primary-secondary line switch arrangement ofthe present invention is means for barring any secondary line switchgroup against seizure by a primary line switch if all the trunksnormally available from the group of secondary line switches are busyand also bar all thesecond? ary line switch groups against seizure by aprimary line switch and indicate by specific tone to the callingsubscriber when all the secondary line switches are barred because ofbeing busy.

There are additional operative features of the present invention whichwill be described in descriptions to follow relating to the exemplaryembodiment of the present invention chosen to explain it, having in mindthat other features not specifically mentioned will be apparent from thedescriptions. The invention is capable of varied modification withoutdeparting from its scope as defined by the subjoined claims.

. Drawings.

' l/Vith reference to the accompanying drawmgs Fig. 1 shows asubscribers automatic telephone A and coin controlled pre-payment deviceP leading to a primary line switch L.

Fig. 2 shows two secondary line switches SL and SL commonly accessiblefrom the primary line switch L, together with sets of chain relays.

Fig. 3 shows a first selector FS and its individually companion timingswitch TS and associated relays accessible from the groupof subscriberhanging up his receiver secondary line switches containing switch SL.

Fig. 4 shows a connector CON and an individually companion timing switchTS accessible from the group of first selectors containing selectors F3It also shows the common clock controlled switch CS.

Fig. 5 shows a called subscribers line switch LS and automatic telephoneA, together with a respectively designated calling meter and calledmeter companion there-to.

Sheets containing Fig. 1 to 5 are assembled in numerical order so thatthe lines extending towards the adjacent margins register.

Fig. 6 shows a preferred modification of Fig. 3.

Figs. 7 and 8 each show a preferred modification of Fig. 4.

Fig. 9 shows a preferred modification of the connector wherein armatures901 and 902 are added on relay 472.

It has been deemed more simple to disclose the preferred embodiment as amodification of a simpler embodiment than in its more in volvcd,preferred form incorporating Figs. 6, 7 and 8.

E gm'pment.

The telephone A is of the well known automatic common-battery seriestype, having an individual pro-payment coin device or box P of wellknown type as used in the Bell telephone system in the Chicago,Illinois, exchange and other places, however, the said device having anadditional spring 14 wired in accordance with the present invention.That is, the mechanism for actually depositing or refunding the coin isold, though the wiring arrangement and control of the magnet foroperating its armature for depositing or refunding the coin belongs tothe present invention.

The line switches L, SL, SL' and SL are of the well known Lamb generalclass as described on page 53'of the Third Edition of Hersheys AutomaticTelephone Practice, however, modified in details in accordance with thepresent invention.

The selector FS is of the well known Strowgergeneral class (sometimestermed a Powell selector), however, modified 'in accordance with thepresent invention; A Powell selector is illustrated on page 60 of thesaid Hershey book.

The switches TS and TS have the general mechanical details of the lineswitch L, however, modified in accordance with the present invention.

Theconnector shown in Fig. 4 is of the well known Strowger general classas illustrated on pa e 38 of the said Hershey book, however, modi ed inaccordance with the present invention.

The clock controlled device CS is like shown inFig. 4 and also describedin my copending application Serial No. 191,578, filed a May 16th, 1927,and thus revolves its contive with the connector CON, the system being athree-digit system, chosen as the simplest to illustrate the presentinvention. However, it will be understood that the commercial embodimentof the invention would,

usually involve four or more digits, and under that condition one ormore well known Powell selectors or other suitable. selectors will beintroduced between the selector F3 and the connector CON; one suchselector for each digit over three. Also, a well known socalled trunkrepeater may be introduced between the selector FS and the connector CONat any point, without afiecting the operation of the present inventionin its essentials.

Operation.

The voperationof'the system will be fully understood from exemplarydescriptions of the circuit and switch operations in certain assumedcalls, having in mind that while a single selector and connector isshown it is only-one of a group of similar switches, since the systemcontemplates a plurality oflike calls in simultaneous existence.

- Initiating a call from telephone A to telephone A.

The calling subscriber will remove the receiver of telephone A from theswitch-hook.

There will be no operative efiect resulting from this until a coin isplaced in the coin chute (not shown) of the device P to assume thedotted position 9 which will cause the normally free springs 12, 13 and14 to engage together as indicated by the dotted positions thereof. Thiscloses a series path from ground, armature 15, 'springs'14 and 13,receiver and transmitter of telephone A, armature 16 to the windin ofslow-releasing line relay 17, the latter sai relay actuating. Thewindings of the polarized 'electro-magnet 18 of the device P will be ina path from ground to the lower line talking conductor closed by thesprings 12, 13 and 14.

The line switch L will operate in the well known manner to seize thetrunk its' wipers are shown resting upon or will rotate in a huntingoperatlon and selze the first idle trunk line tested through theoperation of. seizing (also termed brldge-cut-oflvkrelay' The lineswitch L has access to two groups of trunks corresponding to two groups0 secondary line-switches of which SL and SL' are each oneswitch-of thetwo groups, re-

speetively. It will be first assumed that the to ground. The latter saldmagnet, due toits polarized property operates to refund the trunkleading to the 'secondaryline switch SL is seized so that the winding ofslow-rewhereupon the switch SL will operate in the well known-manner andseize the trunk its wipers are shown resting upon or will rotate in a:hunting operation and seize the first idle trunk line tested through theoperation of seizing relay 204.

It will be first assumed that the trunk lead ing to first selector FS?is seized, so that the windingsof line relay 301 is now ina seriespath'including the telephone A and the upper winding ofelectro-polarized relay 302. The switches-L and SL are maintainedoperated in the well known manner due to the slow-releasingcharacteristic of relays 17 and 201until slow-releasing release relay304 actuates and applies ground from its armature 305 over release trunk306 to the winding of slow-releasing relay 307, the latter said relayactuating to apply ground from armature- 308 normal position of wiper315 of the wiper group 312 to 316 on shaft 317 of the timing switch TSCalling subscriber abandons call.

If the calling subscriber now abandons the call by replacing hisreceiver on the switch-hook, the relays 301, 304 and 307 will deactuatein sequence. Before relay 307 deactuates ground is applied fromretracted armature 305, armatures 319, 320, bank terminal 321, wiper316, interrupter armature on motor magnet (designated MM) of the timingswitch TS causing the wipers to be stepped to the second bank position.WVhcn' the armature 308 retracts its ground is applied through armature322 to ,bar 323 ongaged by wiper 316 so that the motor magnet will drivethe wipers on shaft 317 by interrupter action to restore. them to thedrawn position.

It will be noted that wiper 315'maintains ground on bar 324 and toconductor 309 after the retraction of armature 308 to hold the switchesL and SL in seizure. However,

when wiper 312 encounters bank terminal 325 it causes relay 326 tooperatively energize to attract allits armatures, but for the soleobject at this time of completing a path armature 327, upper winding ofrelay 328 armature 329, lower talking conductor through the winding ofpolarized magnet 18 coin to the subscriber, in the well known manner.The springs 12, 13 and 14- are now f from ground through negativebattery BB,"

conductor 309, whereupon the switches L I and SL restore subject tonormal use by reason of relays 20 and 204 deactuating, re-

spectively.

In this connection it will be noted that when the relay 326 actuates thearmature 332 (which is adjusted to make first) will close ground derivedthrough common retardation coil 334 to re-energize the upper winding ofrelay 301. However, due to the rapid movement of the wiper 312 thisclosure is maintained a very brief time; insufiicient for the relays 304and 307 (which are somewhat slow in attracting their armatures due tothe stated slow-releasing characteristic affecting the actuation) toboth actuate to cause ground to be on bank terminal 321 when the wiper316' returns. Otherwise (with ground on bank terminal 321), the wiperson switch T8 would be caused to thereupon make a false cycle ofoperation, however, to no operative confusion, since the call iscompletely abandoned when the wiper 315 moves off bar 324. The object ofarmature 332 and coil 334 will appear presently.

Calling subscriber elects to complete call in place of abandoningitSends first digit.

If the calling subscriber in place of the assumed abandoning of the callelects to complete it he will operate his calling device in accordancewith the first digit 1, which will cause relay 301 to momentarilyretract its armature 335, applying ground through armatures 336 and 337,winding of slow-releasing series relay 338 to the winding of thevertical magnet (designated Vert. M.). This will raise the shaft 340carrying wipers 341 to 343 into alignment with the first level of bankterminals of which terminals 345 to 347 constitute the first setcooperative with wipers 341 to 343, respectively. If it is assumed thatthe connector CON (corresponding to bank terminals 345 to 347) is idle,and

having in mind the well known selective and test circuits present in theselector F8 of the present invention, the connector CON will be seizedby the actuation of switching relay 350, whereupon the relay 301 willbecome disconnected. v

The windings of the line relay 401 of the connector are now in serieswith the telephone A, there being no intermediate afiecting attachments;Slow-releasing release relay 402 is now operatively energized byarmature 403, which causes armature 405 to apply its ground to therelease trunk 406, bank terminal 345, wiper 341, armature 351 to thelower winding of relay 350, for maintainin the selector FS in seizureand the relay 307 energized, efore a ma ure 3 5 retracts, so

that no lapse of ground on the release trunk 306 occurs.

Gatling subscriber sends last two digits to set the connector.

The operation of the connector, effective responsive to the callingsubscriber sending the last two digits 11 of the called telephone numberbeing well known, in view of the stat-V ed reference to Hersheys book,the detailed operation of the connector in effecting con nection to thecalled line leading to telephone A will be understood. It will thereforebe assumed that the wipers 407 to 410 are now resting on bank terminals411 to 414, respectively. the connector specific to the presentinvention will appear presently.

The armature 415 now applies its ground to operate the line-cut-ofi'relay 501 of the line switch LS and to place a guarding busyground onthe private normal conductor 502 and its multipled bank terminals.Ringing current from source designated R. Gen. in Fig. 4 is now beingapplied effective to the signal bell of the called telephone A in thewell known manner.

nector (in view of the present invention) responsive to the calledsubscriber removing 'hisreceiver from the switch-hook in responding tothe call, reference is made to the clock operated device CS This devicehas a grounded contact-arm 416 which revolves making a single cycle in atwenty-four hour period, as has been referred to before. It showstwenty-four equally angular segments; one for each hour, though it willbe understood that the segments may be of any convenient angular size,corresponding to any desired period of the day, to exercise the desiredcontrol. The switch-arm 416 is shown resting on the segmentcorresponding to 12 oclock noon to 1 oclock p. m. The segments from loclock a. m. to 6 oclock a. m. are multipled together and connected tothe switch-arm 417. The segment corresponding to 6 oclock a. 1n. to 7oclock a. m. is connected to the switch-arm 418, and the seg- ,conductor420 when the contact-arm .416 is resting upon the corresponding segmentgroup 421 and segments 422 and 423. Likewise, when the switch-arms 417to 419 are in the dotted positions it provides for ground- Otherfeatures and modifications of and lock by its upper winding and armatureing conductor 425 when the contact-arm 416 is resting upon thecorresponding segment group 421 and segments 422 and 423. That is tosay, during the twenty-four day conductor 420 or alternatively conductor425 will be grounded by the contact-arm 416 in accordance with apre-arranged schedule which may be varied at will, as for example, forthe different days of the Week and for various holidays in accordancewith published schedules. In view of the reference to Fig. 5 of mycopfndingapplication Serial No. 191,578, filed ay 16th, 1927, it isthought more detailed discussion of the contemplated modifications ofthe device CS covering multiple and fractional hour segments will not benecessary in impartin a comprehensive disclosure of the device 05. i i

It will 'be noted that when conductor 420 is grounded all armaturescorresponding to 427 in the connector group will be grounded, whichprovides for operatively energizing the reversing relay 428 and lockingit to the release trunk 406, when the called subscriber responds, for anobject which will appear presently. v r I And, it will be noted thatwhen the conductor 425 is grounded all armatures corresponding to 430inthe connector group will be 7 grounded, which provides for applyingthis ground through armature 431 to bank,terminal 432 on switch TS, foran will appear presently.

Subscriber on owlleii' Zine responds.

It will be assumed that the call is made switch arm 417 is in theposition as drawn, and therefore the conductor'420 is grounded. When thesubscriber on the called line removes his receiver from the switch-hookthe ring-cut-ofi' relay 435 will operativel'yenergize to disconnect theringing current and cut-through the talking conductors. Ground fromcontact-arm 416 will be applied through armature 427 to the lowerwinding of relay 428 causing the latter said relay to actuate 436 to therelease trunk 406, reversing the direction of current applied throughthe calling telephone A. This will cause the current in the upperwinding of relay 302 to energize cumulatively with the lower windingthereof, thereby attracting the armatures thereof. The current in thepolarizing (lower) winding of relay 302 is augmented by theshortcircuiting of resistor 353 by the upper armature of said relay 302,which makes first, the

polarizing winding then being able to sustain the armatures regardlessof the direction of current in the upper winding.

In this connection, it will be noted that the ground interrupter V1revolves at a speed which varies with the time of day and may beconsidered similar to and operated and object which 'versation vor beprepared to insert another controlled like interrupter 16 of my saidcopending application. .The ground interrupter CI revolves at constantspeed and is similar to and corresponds to interrupter 78 of my saidco-pending application.

I .The relay 302 actuating and locking responsive to the subscriberonthe. called line removing his receiver, ground impulses from interrupterVI are appliedthrough arma tures 354, 355, bar 356, wiper 314 lowerWind-= ing of relay 328, armature 327 to positivedeposit battery DB toground, the relay 328 operating responsive to the ground impulses fromthe interrupter'VP. The armature 357 V will always be passed over at aconstantrate occupying a substantially uniform time for alltimes of'theday. I

Advane tone or definite time before end of period.

At the time wi or 314 engages bar 358 wiper 313-engages ba terminal 359so that-tone from source PT will -be applied through Q wiper 313,armature 360 tothe lower talking conductor, audible to the parties tothe connection. This tone apprises that asuhstantially definite timeremains within. the 'ensuing period before, the coinwill be deposited inthe company till andthe connection thereafter broken down, and-toterminate the concoin for a succeeding period.

Deposit of the eoinz'n the company till.

When the wiper 312 engages bank terminal 325 and armature 357 thereafterattracts, the relay 326 will actuate as-before described; this timeapplying positive deposit battery DB from-grojund, armature 327, upperwinding ofrelay 328, armature-329 lower talking conductor, winding ofpolarized magnet 18 to ground, the armature of the latter said.

magnet moving. in the direction to deposit the coin in the company till.This opens the circuit path through the telephone A at springs 13 1'4.Under ordinary conditions,

' this would-deenergize the line relay 401 in the connector andcause theconnection to be destroyed. However, it will appear presently that underthe present condition the connection will not be forthwith destroyedj Atthe same time that the coin is deposited in' the companytill the tonesource FT is applied through bank terminal 361, wiper 313, armature 360,to the lowertalking con:

'ductor, audible to'the parties ofthe connec tion, apprising them thatthe period has about terminated and that a short time remains in whichto deposit a coin for a continuation of the connection or it will bedestroyed by selfapplied automatic means involved in the switch TSHowever, when the wiper 313 moves to bank terminal 362 the retardationcoil 363 is bridged across the talking path to maintain the relay 401energized in order to maintain ground on the release trunk 406 so thatthe connection will not be destroyed atthis time. If there is no coin inthe pre-pay ment coin chute of device P at the time wiper 313 moves frombank terminal 362, and the bridge including coil 363 is thereby opened,there will be no path for energizing the relay 401 so it will deactuateand the switches will restore in an obvious manner, in View of thereferences to well known switches.

It will be noted here that at the time relay 326 actuated to efiect thedeposit of the coin in the company till the armature 329 opens theenergizing circuit for relay 401, and the spring 14 of the prepaymentdevice P also does this, so that ground applied through the commonretardation coil 334 and armature 332 to the upper talking conductorserves to main-' tain the relay 401 energized by way of a new path.

Seco'nd coin deposited maintains connect-ion.

- terminal 362 there will be an energizing circuit path through thetelephone A when the bridge including the coil 363 is opened, having inmind that the parties may converse past the said bridge until theconnection is destroyed, the condenser 330 maintaining the talking pathoperative while the armature 329 is attracted for a brief time butsuflicient to operate the magnet 18 of the prepayment device P.

Timing of call starts when called subscriber responds.-Oalled subscribermay assume call charge on his called meter in lieu 0 f callingsubscribers meter.

The switch TS starts responsive to the relay 302 actuating when thecalled subscriber responds' It will be noted that this is due to theswitch-arm 417 being in its drawn position, indicative that all calls atthat hour are positively paid for by the calling party. However, had theswitch-arm 417 been in the dotted position wherein the conductor 425 isgrounded in place ofconductor 420, the charge would be assessed to thecalled subscriber, unless the called subscriber'by a specific manualoperation, as by momentarily depressing key 505, transfers this chargeto the calling line as will appear presently.

It will be noted that the battery energizing the transmitter on thecalled subscribers'telefunction, while armature 430 applies groundthrough armature 431 to bank terminal 432. The wipers 445 to 448 onshaft 449 being in the drawn position the said ground application willbe applied through interrupter armature to the motor magnet MM causingthe wipers 445 to 448 to move ed to first offnormal bank positionwherein wiper 448 is resting on bar 450 and the motor magnet MM is thusunder the control of ground interrupter VI corresponding to interrupterVI in general characteristics and variations of speed with the time ofday; in fact maybe the same interrupter as VP. In the same manner theground interrupter CI corresponds in general to interrupter C1 in fact,may be the same interrupter as C1 However, it will be understood thatthe operating concern may desire to grant special rates to subscriberswho desire to pay for calls made to them at certain predetermined hoursand moreover, to have these rates comprehend a shorter holding time thanapplied to general calls paid for by the calling party. Subscribersreceiving orders from housewives in the early morning hours before thebusiness or logical peak occurs and who have, as a rule, no occasiontohold the connection long would come under this class. Under thisarrangement the ground interrupter VI would be operated at a speed toeflect faster ground impulses during such times when the calledsubscriber pays for the call and the pre-pay ment is accordinglyrefunded, as will appear.

Meter of called subscriber paying for incoming callvregisters aplurality of times for the period.

Itwill be noted that if the called subscriber responds under thecondition of the switcharm 417 bein 'fin the dotted position the relay428 will n'ot be caused to actuate to in turn cause the relay 302 toactuate to start the movement of the switch TS. As the wiper 445 engagesbank terminals 452 to 456 successively five applications of ground willbe made through wiper 445, armature 457, wiper 407, bank terminal 411 tothe called meter 507, registering five points for the predeterminedperiod. The parties to the connection will be apprised of the definitetime before the termination of the period when tone source PT is appliedthrough bank terminal 458, wiper 446, armature 459 to the lower talkingconductor, and again apprised just beplied. The interrupter-s VP and C1are constru'cted so that the ground applications therefrom are briefwith respect to the time between the ground applications.

The interrupter-s P1 and FF are so timed with respect to the interrupterCl" that they will very briefly apply tone while the wiper 446 isresting on bank terminals 458 and 460, respectively, the interrupter PIbeing constructed to apply the tone from source. PT even more brieflythan interrupter FI admits of the tone from source FT to be applied. Theinterrupters VI and C1 are constructed so that the ground applicationstherefrom are brief with respect to the time between the groundapplications.

It will be noted, in this connection, that the wiper 312 is grounded butbriefly at each stepping time so that the relay 826 is only brieflyenergized while the wiper 312 rests on bank terminal The same holds forthe wiper 4.45 so that the called meter 507 of the called subscriber'sline will be only momentarily energized as the wiper engages the bankterminals 452 to 456 for a larger time, respectively.

Number of assessments against the calling subscribcfis Zinc registeredon meter specific to his Zinc.

In addition to or in lieu of the pro-payment coin device P a call meter25 is installed companion to the line switch L. It will be noted thatonly if the relay 302 act-uates responsive to the relay 428 actuatingwill ground on armature 370 be applied through armature 371, conductor37.2 and over the obvious circuit path to the Winding of the meter 25,operating it one time. That is, the meter 25 will record the number ofcoins in the pro-payment device 1, or the number of periods used if thepro-payment device P is not employed. The device P may therefore bedispensed with and the subscribers line connected directly fromtelephone A to armatures 15 and 16 and therefore. not de pendent uponthe closure of springs 13 and 14. The meter 25 may be common to a groupof calling lines.

85110 to encountering his Zine busy.

Let it be assumed that when the private wiper 4-08 of the connector isset upon the bank terminals of the called subscribers line it is busyguarded by ground being on the private bank terminal 412. The busy relay471 will lock, having in mind it may be actuated before the wiper 408 isset upon the bank terminal 412, due to passing over a grounded bankterminal. Slow-releasing rotary relay 472 will be actuated during theoperation of the rotary magnet (designated Rot. M.), and for a timethereafter consistent with its slow- ,Teleasing period, after theimpulses to the rotary magnet cease. Vith the relay 471 actuated.applying busy tone to the calling line andthe relay 472 deactuated,ground through switch-arm 473 is applied through armatures 474 and 4:75,wiper e107, hank terminal -l1l to the called meter 50?. therebyassessing one point thereon. The n eter 507 may be common to a groupof-ca'led lines.

lV/zcf/rcr the charge for ca '11!!! be asscsscrl to busy cal/ed line asdependent upon, time of (lay cu?! is made.

The switch-arm 473 maybe variously set by the central ollice attendantin accordance with ate schedules. For example, if the switch-arm 47 3 isset upon the terminal 475, the assessment against the called line for anencountered busy condition thereof will depend upon the conductor 42:")being grounded in accordance with the time of day. And if theswitch-arn'i 4.73 is set upon terminal 476 the latter said assessmentagainst. the called line will depend upon conductor 420 being groundedin accordance with the time 01 day. And if the switch-arn'i 473 is setupon the terminal 477 no latter said assessment will be made against thecalled line.

Means for refunding coin subscribe-1 Zinc cannot be ca'tcncleel to firstaclccfo? (Inc to busy trunk condition-11 secondary Zine switch cannot bescized 110 outgoing trunks accessible therefrom, are idle.

It will he noted that a set of chain relays 205 to 209 are companion tothe group of trunks accessible from the group of secondary line switchesof which switch SL is one. Also, that these are respectively energizedwhen the corresponding private terminals are grounded, so that conductor210 will begrounded only when all the trunks accessible from switch SLare busy. That is. relay 212 will be actuated when its correspondinggroup of trunks are busy.

Also, it will be noted that a set of chain relays 215 to 215) arecompanion to the group of trunks accessible from the group of secondaryline switches of which switch SL is one. Also, that these arerespectively energized when the corresponding private terminals aregrounded, so that conductor 220 will be actuated each release trunkconductor as 231 is busy-grounded to bar it from seizure by a lineswitch as L, there being a direct connection from conductor 220 to theresting contacts of all armatures corresponding to 235. This ground isremoved from the release trunk conductor 231 by the attraction of eitherarmature 235 or 236. Thus, normally all idle release trunk conductors231 will be tied to conductor 220 and each untied as the correspondingswitches are seized. However, a switch of the group containing switch SLcannot be seized if the conductor 220 is grounded by the closure of thechain ground by relays 215 to 219.

The release trunk conductors as 230 are not normally tied together sincethe conductors as 238 are individual to each armature as 240 and anarmature as 241 on relay 212.

,That is to say, if all trunks of a group accessible from line switch SLor SL are busy, the switches SL or SL, as the case may he, cannot beseized. This is in order to prevent a secondary line switch being seizedin a group wherein there is no idle outgoing trunk as denoted by theconductor 210 or 220 being grounded. The conductor 220 may be falselybusy-grounded at the instant of seizure of an idle secondaryline switchas SL', but only for a very brief, almost inappreciable time so far asany affecting operative function is concerned. This would only endureafter the idle trunk is seized until the armature corresponding to 235thereofattracts to free it from conductor 220.

It will be noted that bank terminals 245 and 246 accessible from switchSL lead to the tone source 8T to minus (refunding) battery RB andthrough retardation coil 250 to the latter said battery. This alsoapplies for bank terminals 247 and v 248, respectively. The private bankterminal 251 is normally connected through armatures 252 and 253 toground to guard the bank terminals 245 and 246 against seizure. Theprivate bank terminal 255 is normally connected through armatures 256and 253 to ground to guard the bank terminals 247 and 248 againstseizure, it being noted that armature 253 is common to the grounding ofboth private bank terminals 251 and 255. g

It will be noted that when all trunks accessible from switch 'SL arebusy theterminals 245-and 246 are unguarded, and that when all trunksaccessible from switch SL' are busy the terminals 247 and 248 areunguarded. This is so in the event there is a sole idle trunk accessiblefrom either switch SL or SL and two line switches as Ls ize a switch asSL or S L wherein but one of the switches will be enabled to seize thesole idle trunk the other switch involving the futile extension willthen be caused to seize the bank terminals corresponding to tone sourceST The calling subscriber of the futile call will thus be apprised bythe distinctive tone from th latter said source. Also, the refundingbat- I tery RB applied through the retardation coii 250 will operate themagnet 18 in the device P to refund the coin to the calling subscriber.In this connection, it Will be noted, that the subscribers line willbecome opened at spring 14. No ground being applied back over theprivate terminal 251, or 255 as the case may be, the switch as SL, orswitch SL as the case may be, would not in any event remain in seizurebeyond-the sustaining period of the relay 201, or 260, as the case maybe.

Calling subscriber notified by specific tone if initiated call is futilebecause of all trunks outgoing from his primary Zine switch or thesecondary Zine switches are busy, respectively.

In the event, when all trunks normally accessible from the secondaryline switches SL and SL'- are busy, the relays 212 and 222 to 224 willbe actuated and ground chained to actuate relay 265. This Willremove theground applied from the resting contact of armature 253, so that notonly will the ground he removed from the bank terminals 245 and 255, butground will also be removed from bank terminals as 31 of the primaryline switch L to unguard bank terminals as 32 and 33, so that anysubscriber now initiating a call wherein no extension can be made due toall outgoing trunk paths being busy, the terminals corresponding to 32and 33 will be seized and distinctive tone from source PT appliedaudible to the calling subscriber. The minus (refunding) battery RB"applied through retardation coil 275 will cause the refunding of thecoin in the same manner as when a refund is made by battery RB appliedthrough coil 250.

It will be understood in this connection that all terminalscorresponding to 251, 245 and 246 of the group containing switch SL willbe in multiple, respectively. The same holds for-all terminalscorresponding to 255, I

247 and 248 of the group containing switch SL'. And the same holds forthe primary line switches as L wherein all the terminals correspondinto.31, 32 and 33 are tied together, respectlvely.

It will thus. be clear that not only are the primary line switches as Lbarred from seizing a secondary line switch wherein there is at the timeno idle outgoing trunk available from the secondary line switch, but inthe event of an all busy trunk condition outgoing from the secondaryline switch seized occurring after the seizure of a secondary lineswitch the calling subscriber concerned will cific tone and will havehis pre-deposited coin refunded forthwith.

Also, in the event there are no idle trunks outgoing from the primaryline switch as L the calling subscriber concerned will be apprised ofthe fact that the call is futile by a specific tone and have hispre-deposited coin refunded.

It will be noted that the present invention comprehends armatures 240,271 and make contact 272 of switch SL, and armatures 235, 236 and makecontact 275 of switch SL',

together with interlinked circuits, having in mind that the line switchL-is not new in the art and in itself without consideration of itscooperative circuits is not a part of the present invention. What isshown in switches SL and SL' .beyond what is shown in the switch Lbelongs to the present invention.

Preferred modificatiom.

Fig. 6 shows a preferred modification of Fig. 3 wherein an addedarmature 601 on relay 326 causes added relay 602 to actuate and lock byarmature 605 to the release trunk 309 so that the ground interrupter VIis disconnected and the-ground interrupter VI is connected in-its placeb armature 604. The latter interrupter whi e variable with the time ofday, as is interrupter V1 runs slower so that the time required for thewipers 312 to 316 to pass over the space embraced by bar 356 will belonger under the influence of the interrupter VI than under theinfluence of the interrupter VI That is, for the same time of day theperiods after the first for a maintained connection will be longer forthe same assessment. The interrupters VI andVI may have speeds which arecorrespondingly variable during the day. Thus, the percentage increasein the allowable time for succeedin periods over the initial period maybe uni orm, but of course,

this is not necessarily so. I

Fig. 7 shows a preferred modification of Fig. 4 wherein when wiper 445applies ground to bank terminal 470 relay 701 is caused to lock byarmature 702 to the release trunk 406. Armature 703 disconnectsinterrupter- VI and substitutes interrupter VI therefor. The latter.interrupters may bear the same relation to each other as interrupters-VIand VI in Figs. '3 and 6, for a similar object, but-with respect toassessments on the called meter as 507 'of the line called.

Fig. 8 shows the retardation coil 440 in Fig. 4 changed to a relay 801havin an armature 802 and the relay 441 change to, relay 803 havingcumulative windings in place of differential, and the armature 804 ofrelay 803 provided witha grounded resting contact 1 n place of a makecontact. The relay 803 1s marginally adjusted. In the event the calledamaees subscriber at telephone A wishes to cause the relay 428 to lockhe will momentarily depress button 508 to remove the short-circuit fromthe resistor 509 to attentuate the strength of current traversing thecumulative windings of marginally adjusted relay 803 so that it willretract its armature 804, while armature 802 remains attracted, thuscausing a ground impulse to be applied to energize the upper winding ofthe relay 428 to cause the reversal effective to actuating relay 302.That is, in place ofapplying ground by means of button 505 the inclusionof resistance involved in the resistor 509 is employed. One or theotherbutton 505 or 508 will not be employed.

Fig. 9 shows a preferred modification of the connector wherein armatures901 and 902 are added on relay 472. -Armature 901 energizes addedslow-releasing relay 903, so that relay 903 will sustain a short timeafter relay 472 deactuates. During the time relay 903 is actuated whilerelay 47 2 is deactuated, tone from source T is applied to the calledline, whether it is idle or busy, so that if it is busy the partythereon will be apprised that a calling party is seeking connection withhis line and will perhaps hasten the termination of the ensuing call sohis line may be available if a subsequent attempt to connect with it ismade. i

The conductor from the switch-arm 47 3 is run to the armature 905 sothat the path from switch-arm 473 to the make contact of armature 474 isonly closed while relay 903 is actuated. This obviates energizing thecalled meter 507 for the entire time the con nector is left intoselective relation to the busy called line.

In this connection, it is to be understood that the said preferredembodiments, excepting that disclosed by Fig. 8, are to be assumed aspart of the exemplary embodiment, shown as modifications in order tomake the descriptions as simple as possible. That is, the preferredembodiments, so termed, are not intended as merely possible alternativeembodiments, though obviously they may be omitted without departing fromthe spirit of the invention defined by certain subjoined claims whichmay not require all disclosed structure to support-them.

I claim 1. In an automatic telephone system, a connective switch, acalled line, a test terininal of the called line, means forautomatically operating the connective switch to effect selection of andseizure of the called line, means responsive to a specific electricalpotential existing on sa1d test termiml for barring the seizure of theselected called line, means for applying and removing said specificelectrical potential from sa1d test terminal, a call meter device forthe called line, and means for operating said device to record a barredcall to the called line only if said switch is operated into selectiverelation with the called line and said switch is prevented from seizingthe called line-due to the said specific potential existing on said testterminal thereof.

2.' In an automatic telephone system, a connective switch, a calledline, a test terminal of the called line, means for automaticallyoperating the connective switch to effect selection of and seizure ofthe called line, means responsive to a specific electrical potentialexisting on said test terminal for barring the seizure of the selectedcalled line, means for applying and removing said specific electricalpotential from said test terminal,.a call meter device for the calledline, and means for operating said device to record a barred call to thecalled line only if said switch is operated into selective relation withthe called line and said switch is prevented from seizing the calledline due to the said specific potential existing on said test terminalthereof, and automatic 'means for causing the operation of last saidmeans onlyguring certain predetermined periods of the ay. 7

3. In an automatic telephone system, lines, a primary line switch foreach said line, a group of secondary line switches accessible from saidprimary line switches, specifically distinctive tone sources for theprimary line switches and for the group of secondary line switches,another switch accessible from said secondary line switches, meansresponsive to initiating a call on a random one of said lines forcausing the corresponding primary line switch to seize a said secondaryline switch and for the seized secondary line switch to thereupon seizesaid other switch, means for barring a seized said'switch from being further seized by another said switch while the first seizure endures, andmeans for applying the corresponding said tone source audible on theconcerned said line responsive to the initiation of a call on a randomsaid line if the concerned primary line switch is barred from seizingall secondary line switches or ii the secondary line switch seized bythe primary line swi ch is barred from seizing the said other switch. y

4. In an automatic telephone system, lines, a primary line switch foreach said line, a

'group of secondary line switches accessible from said primary lineswitches, sources of direct current specific to the primary lineswitches and to the group of secondary line switches, another switchaccessible from said secondary line switches, means responsive toinitiating a call on a randomvone of said lines for causing the primaryline switch to seize a said secondary line switch and for the seizedsecondary line switch to thereupon seize said other switch, means forbarring a seized said switch from being further seized by another saidswitch while the first seizure endures, and means for applying thecorresponding said current source to a talking conductor of theconcerned said line responsive to the initiation of a call on a randomsaid line if the concerned primary line switch is barred from seizingall secondary line switches or if the secondary line switch seized bythe latter said primary line switch is barred from seizing the saidother switch.

5. In an automatic telephone system, lines, a primary line switch foreach said line, a group of secondary line switches accessible from saidprimary line switches, another switch accessible from said secondaryline switches, means responsive to initiating a call on a random one ofsaid lines for causing the corresponding primary line switch to seize asaid secondary line switch and for the seized secondary line switch tothereupon seize said other switch, means for barring a seized saidswitch from being further seized by another said switch while the firstseizure endures,

and means for applying a tone audible on the;

said line responsive to the initiation of a call on 'a random said lineif the concerned primary line switch is barred from seizin all secondaryline switches or if the secondary line switch seized by the latter saidprimary line switch is barred from seizing-the said other switch. Y

6. In an automatic telephone system, lines,

a primary line switch for each said line, a

group of secondary line switches accessible from said primary lineswitches, another switch accessible from said secondary line switches,means responsive to initiating a call on a random one of said lines forcausing the primary line switch to seize a said secondary line switchand the seized secondary line switch to thereupon seize said otherswitch,

means for barring a seized said switch from being further seized byanother said switch while the first seizure endures, and means forapplying a' source of direct current to a talking conductor of theconcerned said line rcsponsive to the initiation of a call on a randomsaid line if the concerned primary line switch is barred from seizingall secondary line switches or if the secondary line switch seized bythe latter said primary line switch is barred from seizing said otherswitch.

7 In an automatic telephone system, lines;

a line switch, other switches, a source of direct current, anotherswitch accessible from said line switch and said other switches, meansresponsive to initiating a call on one of said lines for causing saidline switch to seize said another switch, means for barring said anotherswitch from beingfurthe'r seized by one of said other switchesresponsive to said seizure only while said seizure endures, and meansfor applying said source of current to a talking conductor of any saidother switches seeking to seize said another switch when it is barredagainst seizure.

8. In an automatic telephone system, a group of line switches, a groupof lines accessible from said switches, a common conductor, a chainground closed from said common conductor, an antecedent switch havingcommon access to the switches of said group, a private busy conductorindividual to each switch of said group for barring the correspondingswitch against seizure by said antecedent switch, means for conductivelyconnecting the private conductors of all switches of said group whenidle to the common conductor, means for closing said'chain ground toapply busy ground bar to all switches of said group to prevent theantecedent switch from seizing an idle switch of said group only if allthe said group of lines accessible from said group of switches are busy,and means for disconnecting the private conductor of any switchresponsive to the seizure of the corresponding switch by the antecedentswitch, the said seizure being possible only when the switch seized isidle and there is an idle said line accessible from the switch seized.

9. In an automatic telephone system, a rotary line switch, a set ofmovable wipers of the switch, sets of fixed terminals of'thc switchswept by said wipers moving in a single direction, the wipers constantlyengaging a random set of said fixed terminals, a line relay of theswitch, a wiper switching relay of the switch, a group of linescorresponding to said fixed terminals, means for making random ones ofsaid lines busy, means for preventing the wiper switching relay fromoperating when the wipers are resting upon the terminals of a busy saidline, an antecedent switch having access to said switch, directivelycontrolled means including said antecedent switch for causing the saidrelays to operate only when the wipers are resting upon the terminals ofan idle said line, means for guarding the said line switch againstseizure y the antecedent switch it one of said relays is actuated, andmeans for guarding said line switch against seizure by the antecedentswitch if all said lines are busy although neither one of said relays isactuated, the

last said means involving a circuit path including a normally closedcontact on each said relay.

10. In an automatic telephone system, a calling line, a pre-paymentdevice on the call ing line, a called line, a train of automaticswitches for linking a connection from the calling line to the calledline, means responsive to initiating a call on the calling line only ifthe pre-payment device is operated by inserting a pre-payment thereinfor operating a first one of said automatic switches to link apreliminary call' extension towards the called line, means thereafterdirectively controlled over the calling line for operating other of saidautomatic switches to complete said extension to the called line, meansresponsive to abandoning the initiated call for causing the pre-paymentdevice to refund the inserted pre-payment, and means operated responsiveto said initiation only if the first said switch is barred from makingsaid preliminary extension due to all call extension paths therefrombeing barred as busy for 7 causing the pre-payment device to refund theinserted pre-payment.

11. In an automatic telephone system, a calling line, a pre-paymentdevice on the calling line, a called line, a train of automatic switchesfor linking a connection from the calling line to the called line, meansresponsive to initiating a call on the calling line only if thepre-payment device is operated by inserting a pre-payment therein foroperating a plurality of said switches to link a preliminary callextension train towards the called line, means thereafter directivelycontrolled over the calling line for operating other of said automaticswitches to complete said extension to the calledline, means responsiveto abandoning the initiated call for causing the pre-payment device torefund the inserted pre-payment, and means operated responsive to saidinitiation only if one of said plurality of switches is barred frommaking said preliminary extension due to all call extension pathstherefrom being barred as busy for causing the pre-payment device torefundthe inserted pre-payment. I

12. In a telephone system, a calling line, a called line, automaticswitch mechanism for extending a'connection from the calling line to thecalled line a pre-payment device, means dependingupon first operatingsaid pre-payment device by a pre-payment for capacitating the operationof the said switch mechanism, a collecting receptacle and a refundingreceptacle for the pre-payment device, tmeans manually controlled overthe called line only after the calling line has been extended to thecalled line for establishing a talking relation between the calling lineand the called line, means for thereafter at willdestroyingthe extendedconnection and for depositingsaid pre-payment in. the refundingreceptacle, and means controlled over thecalled line at will afterestablishing said talking relation and before destroying said extendedconnection for preventing said pre-payment from being deposited in therefunding receptacle.

III

13. In a telephone system, a calling line, a

- manually controlled over the called line only responsive to destroyingthe extendedconnection for depositing said pre-payment in the collectingreceptacle.

14. Ina telephone system, a calling line, a called line, automaticswitch mechanism for extending a connection from the calling line to thecalled line, a pro-payment device, means depending upon first operatingsaid pro-payment device by a pre-payment for capacitating the operationof the said switch mechanism, a collecting receptacle and a refundingreceptacle for the pre-payment device, means after the calling line hasbeen extended to the calledline for establishing a talking relationbetween the calling line and the called line, means for thereafter atwill destroying the extended connection and for depositing saidpre-payment in the refunding receptacle, means controlled over thecalled line at will after establishing said talking relation and beforedestroying said extended connection for preventing said pre-payment frombeing deposited in the refunding receptacle, and means thereafteroperated at the termination of a predetermined period of time forconversation following the said control of last said means fordepositing said prepayment in the collecting receptacle.

e 15. In a telephone system, a calling line, a called lin'e leading froma central exchange to a gsubscribers station, automatic switch mechanismfor extending a call connection from the calling line to the calledline, a toll assessing device for the called line at the centralexchange. and means controlled over the 4 called line for operating thetoll assessing device after said extension to the called line has beenmade to 'record a toll assessment for the call connection from thecalling line to the called line against the called line Withoutrefording a toll assessment against the calling 16. In a telephonesystem, a calling line, a called 'linc, automatic switch mechanism forextending a call connection from the calling line-to the called line, atoll assessing device for the calling line, a toll assessing device forthe called line, means responsive to a manual operation on thecalledline for operating the toll assessing device only of the called line,and other means operated responsive to a manual operation on thecalledline applied at will while said connection exists for operatingthe toll assessing device for the calling line and for disabling theoperation of the toll assessing device on the called line.

7 17. In a telephone system, a calling line, a called line, automaticswitch mechanism for extending a call connection from the calling lineto the called line, a toll assessing device for the calling line, a tollassessing device for the called line, and means controlled over thecalled line by a manual operation for defining what portions of thetotal toll charge for the call shall be respectively assessed againstthe calling line and the called line on the corresponding said devices.

18. In a telephone system, a calling line, a called line, automaticswitch mechanism for extending a call connection from the calling lineto the called line, a toll assessing device for the calling line, a tollassessing device for the called line, means on the called line manuallyoperated for completing a talking connection between the connectedcalling and called lines and means depending upon the time of day thelast said means is operated for determining Whether the toll charge forthe talking connection will be recorded against the calling line or thecalled line by its corresponding toll assessing device.

19. In telephone system, a calling line, a called line, automatic switchmechanism for extending a connection from the calling line to the calledline, a pre-payment device, means depending upon first operating saidpre-payment device by a prepayment for capacitating the operation of thesaid switch mechanism, a collecting receptacle and a refundingreceptacle for the pre-payment device, means for causing the pre-paymentdevice to deposit the pro-payment in the collectin receptacle in asubstantially predetermined time variable in length depending upon thetime of day the said time durates through, a first. and a secondspecifically distinctive tone source, means for applying one said tonesource audible on the call-' ing line at a substantially predeterminedtime before the termination of said period, and means for applying theother of said tone sources audible on the calling line at asubstantially predetermined time before the termination of said period,the elapsed time between the said applications of the tone sourcesbeingsubstantially constant for a plurality of callsregardless of thefact that the length of thesaid eriod may Vary among said plurality' ofcal s, so that a listener on the calling line will have substantiallydefinite notice of the times remaining of a said period regardless ofthe length of the period.

'20. In an automatic telephone system, a called line, an automaticconnective switch for effecting connection to said called line,

a private terminal of the called line, means for applying a specificelectrical potential to the private terminal indicative of the busycondition of the called line, means responsive to efl'ecting connectionto the called line when it is busy for preventing the switch fromeffecting seizure of the connected called line so that a talkingrelation between the switch and the busy called line is barred, a tonesource, and means operated for applying the tone source to a talking-conductor of the called line responsive to the switch eiiecting connectionto the called line whether busy or idle.

21. In a telephone system, a called line, switch mechanism for extendingconnection to said line, a toll assessing device for the called line,means controlled over the called line for operating the toll assessingdevice, and means dependent upon the time of day the connection is madeto the called line for determining the extent of said assessment.

22. In a telephone system, a called line, switch mechanism for extendingconnection to said line, a toll assessing devicf for the called line,means controlled over the called line for operating the toll assessingdevice,

and means dependent upon the duration of the connection for determiningthe extent of said assessment.

23. In a telephone system, avcalled line, switch mechanism for extendingconnection to said line, a toll assessin device for the called line,means controlled over the called line for operating the toll assessingdevice, and means dependent upon the time of day the connection is madeto the called line for determining whether or not the assessment will bemade.

24. In a telephone system, a called line, switch mechanism for extendingconnection to said line, a toll assessing device for the called line,means controlled for initiating the operation of the toll assessingdevice for causin a plurality of assessments to be successive ly madeagainst the called line, and means controlled over a series path of atalking conductor of the called line at will for preventing further saidassessments being thereafter made while maintaining the connection. 25.In a telephone system, a calling line;- 2. called line, automatic switchmechanism for extending connection from the'calling line to the calledline, a toll assessing device for the calling line, a timing device formeasuring elapsed time, means controlled over the called line forinitiating the operation of said timing device, means responsive to theoperation of said timing device for assessing a toll charge on said tollassessing device, means for periodically reoperating said timing devicefor assessing accruing toll charge on said toll assessing device, andmeans the operation of which is. dependent upon whether the assessmentis the initial assessment for a call or a succeeding assessment for saidcall for determining the length of time the toll assessment covers.

26. In a telephone system, a calling line, a called line, automaticswitch mechanism for extending connection from the calling line to thecalled line, a toll assessing device for the cally reoperating saidtiming device for assessmg accrumg toll chargeon said tell as-' sessmgdevice, and means governed by the time of day the call transpires fordetermining the length of time the respective said assessments cover.

27. In a telephone system, a calling line, a called line, automaticswitch mechanism for extending connection from the calling line to thecalled line," a toll assessing device for the called line, a timingdevice for measurin elapsed time, means controlled over the called linefor initiating the operation of said timing device, means responsive tothe operation of said timing device for assessing a toll charge on saidtoll assessing device, means for periodically reoperating said timingdevice for assessing accruing toll charge on said toll assessing device,and means the operation of which is dependent upon whether theassessment is the initial assessment for a call or a succeedingassessment for said call for determining the length of time the tollassessment 4 covers.

28. In a telephone system, a calling line, a called line, automaticswitch mechanism for extending connection from the calling line to thecalled line, a toll assessing device for the called line, a timingdevice for measuring elapsed time, means controlled over the called linefor initiating the operation of said timing device, means responsive tothe operation of said timing device for assessing a toll charge on saidtoll assessing device, means for periodically reoperating said timingdevice for assessing accruing toll charge on said-- toll assessing'device, and means governed by the time of day the call transpires fordetermining the length of time the respectivesaid assessments cover.

29. In a telephone system, a calling line, a

ing line to the called line, a toll-assessing device for defining apredetermined toll charge against the calling line for the connection tothe called line and for a predetermined duration period of saidconnection, a progressively movable wiper switch for measurin elapsedtime of said connection for 'sai charge, means for thereafter definingan additionalperiod of continued connection by a further movement ofsaid movable wiper switch, and automatic means for varying the length ofindividual successive said periods for a single said connectiondepending upon the duration of said connection.

30. In a telephone system, a calling line, a primary line switch for thecalling line, primary lines accessible from the primary line switch, asecondary line switch for the respective said primary lines, secondarylines accessible from said secondary line switches, meansoperated'responsive to initiating a call on the calling line for causingthe primary line switch to hunt for and connect to a said primary lineand for thereupon causing the corresponding secondary line switch tohuntfor and connect to a said secondary line, means for making saidprimary lines and said sec ondary lines busy,meansforbarringbusysaidlines against connection to by the cooperative said switches, meansresponsive to an all busy condition of said secondary lines forpreventing the primary line switch from connecting to the primary line,and means whereby r'esponsive to an all busy condition of said secondary lines occurring after a primaryline has been connected to by aprimary line switch and before its corresponding secondary line switchhas connected to a secondary line, a busy indication will be applieddiscernible on the calling line to indicate that the calling line hasbeen barred from extension to a said secondary line.

31. In a telephone system, a callingline, a primary line switch for thecalling line, primary lines accessible from the primary line switch, asecondary line switch for the respective said primary. lines, secondarylines acces sible from said secondary line switches, means operatedresponsive to initiating a call on the calling line for causing theprimary line switch to hunt for and connect to a said primary line andfor thereupon causing the corresponding secondary line switch to huntfor and connect to a said secondary line, means for making saidprimary'lines and said secondary lines busy, means for barring busy saidlines against connection to by the cooperative said switches, meansresponsive to an all busy condition of said secondary lines forpreventing the primary line switch from connecting to a primaryline,means whereby responsive to an all busy condition of said secondarylines occurring after a primary line has been connected to by a primaryline switch and before its corresponding secondary line switch hasconnected to a secondary line, a busy indication will be applieddiscernible on the calling line to indicate that the calling line hasbeen barred from extension to a said secondary line, and meansresponsive to the all busy condition of the secondary lines terminatingfor stopping the application of the busy indication and for causing thesecondary line switch to operate and complete the connection from thecalling line to an idle said secondary line.

32. In a telephone system, a calling line, a primary line switch for thecalling line, primary lines accessible from the primary line switch, asecondary line switch for the respective said primary lines, secondarylines accessible from said secondary line switches, means operatedresponsive to initiating a call on the calling line for causing theprimary line switch to hunt for and connect to a said primary line andfor thereupon causing the corresponding secondary line switch to huntfor and connect to a said secondary line, means for making said primarylines and said secondary lines busy, means for barring busy said linesagainst connection to by the cooperative said switches, and meansincluding a circuit path from ground individual to each said secondaryline switch and a contact of a relay of latter said switch responsive toall said secondary lines becoming busy for preventing the primary lineswitch from connecting to a primary line.

33. In a telephone system, a calling line, a primary line switch for thecalling line, primary lines accessible from the primary line switch, asecondary line switch for the respective said primary lines, secondarylines accessible from said secondary line switches, means operatedresponsive to initiating a call on the walling line for causing theprimary line switch to hunt for and connect to a said primary line and-for thereupon causing the corresponding secondary line switch to huntfor and connect to a said secondary line, means for making said primarylines and said secondary lines busy, means for barring busy said linesagainst connection to by the cooperative said switches, means includinga circuit path from ground individualto each said secondary line switchand a contact of a relay of latter said switchresponsive to all said secondary lines becoming busy for preventing the primary line switch fromconnecting to a primary line, and means for disabling said circuit pathat said contact when the secondary line switch is in its connectedcondition with respect to a secondary line. a

34:. In a telephone system, a calling line, a primary line switch forthe calling line, primary lines accessible from the primary line switch,a secondary line switch for the respective said primary lines, secondarylines accessible from said secondary line switches,

means operated responsive to initiating a call on the calling line forcausing the primary line switch to hunt for and connect to a saidprimary line and for thereupon causing the corresponding secondary lineswitch to hunt for and connect to a said secondary line, means formaking said primary linesandsaid secondary lines busy, means for barringbusy said lines against connection to by the co-

